1. Field of the Invention
This invention relates to a process for recovering oil and deoiled particulate solids from a sludge. More particularly, it relates to deoiling a sludge and disposing of the resulting sludge by land farming.
2. Description of the Prior Art
The economic processing of oily sludges for reuse of portions thereof and pollution-free disposal of residues poses a difficult problem. These sludges are usually stable emulsions containing water, oil and particulate solids, for example as produced as by-products in petroleum production and refining.
It is known to process an oily sludge, for example in a sump, by introducing steam therein, after which separated oil is skimmed from the surface and water is decanted from the sump, leaving an oily muck or mud residue. The latter is then removed from the sump in any suitable manner, for example by a suction pump, and is disposed of as desired. This process is unsatisfactory, for reasons including: (1) it is relatively passive in nature and undesirably time-consuming; and (2) results in a deoiled sludge which is much less satisfactory for disposal by the land-farming method.
Other methods for processing an oily sludge include diluting or mixing the sludge with a light hydrocarbon solvent, subjecting the sludge to high temperatures and pressures and the like, but these are, in general, unattractive methods for reasons of economy, explosion hazards incidental to handling light hydrocarbon solvents, liquid-liquid phase separation problems, and the like.
It is an object herein to provide an effective process for deoiling an oily sludge. A further object is to produce from an oily sludge a deoiled solid suitable for disposition thereof by the land-farming method. Other objects will be clear from the example and description below.